Never cut down trees without permission, especially when you’re in areas you are not familiar with that might be protected by the law.

When Mr Foo Suan Pin got a contractor to chop down three fruit trees in his garden in the Holland Road area in September 2007, it did not occur to him that he was committing a crime.

But in February this year, he was slapped with a $6,000 fine after he submitted a plan to the authorities for approval of construction works to his house.
The reason? He had removed trees in a tree conservation area… Sunday Times

Here’s a guideline from Sunday Times as well when it comes to chopping down trees in areas you’re unfamiliar with

1 Do I need to seek NParks’ approval if I want to remove a tree in my garden?

Approval from the National Parks Board (NParks) is needed only if the tree is within one of the two tree conservation areas, or has been deemed a heritage tree. You can call NParks’ helpline on 1800-4717300. If necessary, officers will pay you a visit to inspect the trees.

2 Do private developers need to seek NParks’ approval to remove trees if they wish to develop a plot of land?

Only if the land is within a tree conservation area or has heritage trees.

Private developers must engage a registered architect or professional engineer to submit their proposed layout plans to NParks. These would include the number of trees, tree species, girth and height. The trees to be removed are required to be marked on the plans for NParks’ approval.
3 Does NParks conduct tree pruning or tree removal services for private homes?

The two conservation tree areas in Singapore are the Tanglin-Bukit Timah-Pasir Panjang area and the other is in Changi. They were chosen because of the large number of clusters of mature trees and wooded areas there.

To prevent such things from happening in the future if you are a Landed apartment owner, do make sure your architect firm is well aware of the conservation acts which might have future implication with the law.